Comparison of Variable Rate Prescriptions and Optimum Seeding Rate in Soybean [Glycine Max (L.) Merr] and the Impact of Soybean Seeding Rate on Combine Fuel Use and Grain Loss at Harvest

Download or read book Comparison of Variable Rate Prescriptions and Optimum Seeding Rate in Soybean [Glycine Max (L.) Merr] and the Impact of Soybean Seeding Rate on Combine Fuel Use and Grain Loss at Harvest written by William Patrick Hamman and published by . This book was released on 2019 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soybean [Glycine max (L.) Merr] inputs are continually increasing, and with market values decreasing, producers are forced to find ways to maintain profitability. To address these challenges, soybean producers are interested in reducing seeding rates. However, due to within field variability, it may not be possible to lower seeding rates throughout an entire field uniformly and still achieve the same soybean yield. Variable rate seeding (VRS) of soybean allows producers to adjust seeding rates according to the variability in their fields. However, little is known regarding the accuracy of farmers’ VRS prescriptions. The objectives of this research were to 1) determine the agronomic optimum seeding rate (AOSR) and the economic optimum seeding rate (EOSR) in predetermined management zones, 2) compare the calculated AOSR and EOSR to each producer’s VRS prescription, 3) determine the impact of final plant stand on yield within management zones, 4) identify how soybean plant architecture maintains yield across multiple seeding rates, and 5) determine how plant population impacts harvest, especially combine fuel use and harvest grain loss. In 2017 and 2018, eight on-farm trials were conducted across Ohio. The trials consisted of three uniform seeding rates of 247,000, 346,000, 445,000 seeds ha-1, and a variable rate strip determined by the producers ranging from 198,000 to 445,000 seeds ha-1. The AOSR (yield maximizing) and EOSR (profit maximizing) were calculated from regression analyses for each management zone and field. Agronomic and economic optimum seeding rates ranged from 247,000 to iii 445,000 seeds ha-1 depending on the site-year. Final plant stands varied across site- years, but the calculated agronomic optimum final stand (AOFS) were similar to the recommended AOFS of 247,000 to 297,000 plants ha-1. At lower final stands, soybean yield was maintained by the plants’ ability to grow lateral branches that produced pods. In 2017 and 2018, two management zones were seeded at the calculated AOSR and one zone was seeded at the EOSR, indicating that the assigned seeding rates were not effective for these management zones. Combine fuel use and grain loss at harvest were also analyzed using regression analysis. Soybean grain yield had the largest impact on combine fuel use, increasing as grain yield increased. Plant moisture, grain moisture, branching, and stem hardness did not impact combine fuel use. When final plant populations were reduced, the pods that were closer to the ground were difficult to harvest, which led to increased harvest loss in soybean populations